Vasil V. Popov

From the Bay of Naples to the River Don: the Campanian Ignimbrite eruption and the Middle to Upper Paleolithic transition in Eastern Europe

The Campanian Ignimbrite (CI) eruption, dated by 40Ar/39Ar and various stratigraphic methods to ca. 39,000 cal BP, generated a massive ash plume from its source in southern Italy across Southeastern and Eastern Europe. At the Kostenki-Borshchevo open-air sites on the Middle Don River in Russia, Upper Paleolithic artifact assemblages are buried below, within, and above the CI tephra (which is redeposited by slope action at most sites) on the second terrace. Luminescence and radiocarbon dating, paleomagnetism, and soil and pollen stratigraphy provide further basis for correlation with the Greenland and North Atlantic climate stratigraphy. The oldest Upper Paleolithic occupation layers at Kostenki-Borshchevo may be broadly correlated with warm intervals that preceded the CI event and Heinrich Event 4 (HE4; Greenland Interstadial: GI 12-GI 9) dating to ca. 45,000-41,000 cal BP. These layers contain an industry not currently recognized in other parts of Europe. Early Upper Paleolithic layers above the CI tephra are correlated with HE4 and warm intervals that occurred during 38,000-30,000 cal BP (GI 8-GI 5), and include an assemblage that is assigned to the Aurigancian industry, associated with skeletal remains of modern humans.

Multivariate palaeoecological analysis of a late quaternary small mammal succession from North Bulgaria

The basic assumption of the analysis is that the stratigraphical change of relative abundance of the small mammal species is a phenomenon due to a certain number of environmental factors. In order to reveal these factors and to make some palaeoclimatic reconstructions the following approaches have been used: 1. Analysis of intrinsic structure of the initial data by using principal component analysis (PCA)—delimitation of recurrent groups of species and ordination of assemblages; 2. Extension backward in time of known ecological preference of taxa, forming a particular recurrent group; 3. Comparison of the results with the analysis of assemblages from “known”; (Holocene) environment. On the basis of ecological appearance of particular recurrent groups it is assumed that the main factors are temperatures and effective moisture. The reconstructed values for these environmental factors obtained on the basis of the Holocene recurrent groups of small mammals shows similarity to the recent climate in the area.

Fauna, Zoogeography, and Ecology of Birds in Bulgaria

This paper is the first overview and evaluation of the exploration (1744 to present), composition (records of 96 Neogene taxa, 160 Pleistocene taxa, and 399 recent species), formation (since the Middle Miocene), and recent development of the Bulgarian bird fauna. We discuss composition and changes of the recent avifauna; changes in the composition of the breeding species in the last 100 years; species, which have disappeared or are declining; species with extended breeding range; and new species recently recorded for Bulgaria. We also outline the importance of the Bulgarian territory for the migration and wintering of the birds in Europe, the migration routes, wintering grounds, and the network of the Important Bird Areas. A classification of the avian assemblages in Bulgaria is given using the two-way indicator species analysis, while the application of the ordination-correspondence analysis allowed to study the spatial differentiation of the recent breeding avifauna, and to characterize the bird communities of the main landscapes in Bulgaria

Terrestrial Mammals of Bulgaria: Zoogeographical and Ecological Patterns of Distribution

Our present knowledge of the terrestrial mammals of Bulgaria is reviewed on the basis of published records and original data collected in 1990–2002. The study is based on 93 species of terrestrial mammals. They are classified into four faunal complexes reflecting the influence of historical and environmental factors. The spatial differentiation of the mammalian fauna is considered within a network of landscape territorial units, or natural regions (NRs). Physiographic and climatic indices of each NR are used in the quantitative analyses in order to explore the environmental causes of the observed patterns. The variability of species richness across the NRs does not correlate with environmental variables and seems to depend on the completeness of regional inventory. However, the species richness of carnivores and artiodactyls shows patterns which could be due to the human impact in the lowlands and the greater habitat diversity in the mountains. Faunal differentiation of the Bulgarian mammals is primarily related to the altitudinal gradient and secondarily, to the humidity and continentality of the climate in the lowlands. Detailed analyses are performed on a set of 83 local assemblages of small epigean mammals (pitfall data) from 16 sampling areas. Each assemblage represents a specific habitat type within the sampling area hypothesized as perceived by the small mammals. Conditions within the habitats are described through the environmental variables. The ordination analyses reveal that, again, the composition and structure of the local assemblages are primarily affected by the altitudinal gradient, the secondary group of factors being local vegetation type and humidity. The classification analysis distinguishes five assemblage types. The structure of the local assemblages is affected primarily by the external environmental factors; the role of internal factors, such as competition, could be suggested only in one case. The environmental relationships of species change along the overall gradient. On the basis of the observed patterns we propose a zoogeographical subdivision of Bulgaria into two districts, with two subdistricts each. The changes of the zoogeographical structure of the mammalian fauna in Bulgaria are due to environmental differentiation, modified by human impact since the middle of Holocene